2A Peptide Products

Initially discovered from the foot-and-mouth disease virus (FMDV, a picornavirus), 2A peptide is a self-cleaving peptide 18-22 amino acids long with a conserved C-terminal motif Asp-Val/Ile-Glu-X-Asn-Pro-Gly-Pro. All picornaviruses have 2A peptides but they differ in size and function. The FMDV genome is a single open reading frame encoding a polyprotein and 2A denotes a specific cleavage region within the polyprotein. Co-translational cleavage of the FMDV polyprotein is not mediated by a proteolytic mechanism but rather by "ribosomal skipping" or "StopGO" at the 2A/2B junction. When synthesis terminates at a sense codon, the polypeptide is released before resuming translation at the next codon (1, 2).

Developed for genetic engineering, 2A cleavage has been shown to function in a wide range of eukaryotic cells, and in vivo (3). The 2A peptide is inserted between the coding sequences of at least two genes, enabling the simultaneous expression of multiple proteins from a single plasmid construct. Four variants of 2A peptides have been used in gene expression systems including FMDV 2A (F2A), equine rhinitis A virus 2A (E2A), porcine teschovirus-1 2A (P2A) or Thoseaasigna virus 2A (T2A). Compared to other multi-gene co-expression systems such as IRES, 2A peptides results in stoichiometric expression of different proteins. However, cleaving efficiency and protein expression using the different 2A peptides varies, requiring optimization of polycistronic constructs for experiments.

References

1. Liu Z, Chen O, Wall J, Zheng M, Zhou Y, Wang L, Vaseghi H, Qian L, Liu J. (2017). Systematic comparison of 2A peptides for cloning multi-genes in a polycistronic vector. Scientific Reports. 7. 10.1038/s41598-017-02460-2.

2. Luke GA, Escuin H, Felipe PD, Ryan MD. (2009) 2A to the Fore - Research, Technology and Applications, Biotechnology and Genetic Engineering Reviews. 26(1): 223-260.

3. Markus BM, Bell GW, Lorenzi HA, Lourido S. (2019) Optimizing Systems for Cas9 Expression in Toxoplasma gondii. mSphere. 4(3): e00386-19.